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The Council approved the bill Tuesday by a 12-1 vote. Councilmember Tommy Wells, a Ward 6 Democrat, voted no, saying the bill didn't go far enough to limit the influence of corporate donors.

The bill creates an ethics board with the power to punish members for violations. It also calls for the expulsion of any councilmember who is convicted of a felony, although district voters would have to approve that provision.

The bill was amended Tuesday to allow the council to impeach a member for serious misconduct. Impeachment would require 11 votes from the 13-member council.

Councilmember Marion Barry was one of two members who voted against the amendment.

Thomas has been under investigation for several months since being accused of diverting more than $300,000 in city funds for personal use.

A federal criminal investigation into D.C. Mayor Vincent Gray’s administration was sparked after Sulaimon Brown alleged earlier this year that Gray’s administration paid him to talk badly about then-mayor Adrian Fenty during the campaign.

Brown claimed he was promised a job in Gray’s administration in exchange for criticizing Fenty in the lead up to the election.